Paperback. Pub Date: 2015-12-01 Language: Chinese Publisher: Shaanxi People's Education Press. port operator mental arithmetic speed counting exercises every day (grade next two RJ excellent training Edition) and the traditional port operator different mental arithmetic speed operator training. the traditional port operator mental arithmetic speed counting training methods using a large amount of questions tactical training. repeat the exercise. without regard to method. we talk about speed. so that students feel dull. adding to the burden of their learning. Practice has proved that improve the ability of the port operator mental arithmetic calculation speed can not be accelerated by surprise. but to go through a long training process step by step.